How to Block a Girlfriend's Texts

I just don't know if you're capable of following through on the advice. I'd like to know the stats of this too, because from what it sounds like he said, he often texts with multiple girlfriends and a few of them get racy. And then one solution I would offer up is you could just block everyone. Although after a while flirty text, you'd think they'd be like, what's going on here? We all know the answer.